Biology HESI A2 Practice Exam

Correct Answer: A

Rationale: The correct answer is A: Sucrose. Sucrose is a disaccharide composed of one molecule of glucose and one molecule of fructose. It is formed by a condensation reaction between these two monosaccharides. Fructose (choice B), glucose (choice C), and galactose (choice D) are all monosaccharides, not disaccharides. Therefore, they are incorrect choices for this question.

Correct Answer: B

Rationale: The correct answer is B: Red blood cells lack nuclei. This is because during their maturation process, red blood cells expel their nuclei to make room for hemoglobin, allowing them to carry oxygen efficiently. Nerve cells (A), liver cells (C), and connective tissue cells (D) all have nuclei because they require genetic material for various functions such as protein synthesis, regulation, and repair. Red blood cells, lacking nuclei, are specialized for their main function of transporting oxygen throughout the body.

Correct Answer: B

Rationale: The correct answer is B: Calvin cycle. This process occurs in the stroma of chloroplasts and is responsible for converting carbon dioxide into glucose using ATP and NADPH generated in the light-dependent reactions. Photosynthesis (A) is the overall process, including both light-dependent and light-independent reactions. Germination (C) refers to the process of a seed sprouting into a plant, not the light-independent reaction. The phosphorus cycle (D) is a biogeochemical cycle unrelated to photosynthesis.

Correct Answer: B

Rationale: The correct answer is B: Hominidae. Homo sapiens belong to the family Hominidae, which includes great apes like chimpanzees, gorillas, and orangutans. This classification is based on shared physical and genetic characteristics. Choice A (Animalia) is incorrect as it refers to the kingdom level of classification. Choice C (Mammalia) is incorrect as it refers to the class level of classification. Choice D (Chordata) is incorrect as it refers to the phylum level of classification. The key is to identify the correct taxonomic level for the family that includes humans.

Correct Answer: A

Rationale: The correct answer is A: Anther. The anther is the part of the plant responsible for producing pollen. It is located at the top of the stamen, one of the male reproductive parts of a flower. Pollen contains the male gametes necessary for fertilization. The other choices, B: Style, C: Stigma, and D: Pistil, are all parts of the female reproductive system of a flower. The style is the tube connecting the stigma to the ovary, the stigma is the sticky part that receives pollen, and the pistil is the entire female reproductive structure. Therefore, they are not involved in the production of pollen.